Alexander bernstein



(No Model.)

A. BERNSTEIN. THERMAL GUT-OUT.

No. 433,229. Patented July 29, 1890.

- UNITED STATES PATENT OFFICE.

ALEXANDER BERNSTEIN, OF LONDON, COUNTY OF MIDDLESEX, ENGLAND,

ASSIGNOR, BY MESNE ASSIGNMENTS, TO THE BERNSTEIN ELECTRIC COM- PANY, OF BOSTON, MASSACHUSETTS. l A

'l'HE R MAL CUT-OUT.

SPECIFICATION forming part of Letters Patent No. 433,229, dated July 29, 1890.

Application filed July 28, 1888. Serial No. 281,262. (No model.)

To all whom it may concern.- I

Be it known that I, ALEXANDER BERNSTEIN, of London, in the county of Middlesex, En gland, have invented an Improvement inan 5 Electric Cut-Out or Switch, of which the following description, in connection with the accompanying drawings, is a specification, like letters on the drawings representing like parts. This invention has for its object to construct an automatic electric cut-out or switch which isdesigned to be placed in a shunt to an electric lamp to maintain the continuity of the current should the carbon or filament break.

In accordance with this invention two con- [5 ducting pieces or parts are placed adjacent 2 5 direct contact with the other conducting-piece or so nearly so as to maintain a continuous circuit without sparking. WVhen the switch is placed in shunt to a lamp, the resistance of the compound or material is so great as com- 0 pared with the resistance of the carbon element that only a small proportion of the current goes through the switch; but if the carbon should. break the entire current goes through the switch a and by local heating 3 5 changes the resistance material, thereby enabling the conducting-pieces to come together. Figure 1 shows in plan view an automatic electric switch or cut-out embodying this invention in connection with a manuallyoper- 4o able switch; Fig. 2, a vertical section of the switch and cut-out shown in Fig. 1, taken on the dotted line a: x; and Fig. 3, a cross-section of the automatic cut-out shown in Fig. 2,taken on the dotted line y.

The cut-out consists of a support a, of insulating material, tapped to receive the cylin- (lrical metallic piece b. Another cylindrical metallic piece 0 is placed adjacent to thepiece b, the two pieces being joined by narrow strips d, of vulcanized fiber or other insulating ma- 5o terial. A conducting piston, plug, or piece e is contained within the cylinder 1), it being pressed down by aspring f. The plug c has its outer or lower end reduced in diameter,

as at e. The lower cylinder 0- is socketed to receive a screw it, which has at its upper end a recess for the reception of the small end 6 of the plug 6. This recess is filled. with a compound or material, as 2, normally having a very high resistancesuch, for instance, as

a mixture of oxide of mercury and carbon and the plug 6 is normally pressed by the spring f down upon the said resistant, but

entering the recess.

The cut-out thus described is herein shown in connection with a manual switch, consisting of two plates or n", secured to a circular frame or shell, and to which the line-wires n n are connected, and two plates m m, also secured to said frame or shell, which plates are formed with sockets to receive the cutout. The loop-wires m m are electrically connected to the plates m m, respectively, and the parts 0 and b are also in electric contact with the plates m m. Contact-pens m m are attached to a rotatable post m, which co-operates with the plates on m, and two other contact-pens it are attached to said post m which co-operate with the plates n at when the post is in one position and which are insulated therefrom when in another position. These pens t t are in electrical connection withthe pens m m Two other contactrpens, as 0, are attached to said post m, but insulated from the other pens, said pens obeing connected together and adapted when the post m is in one position to co-operate with the plates n n. With the parts in the position shown the current passes over the line-Wire n pens 0, and line-wire 12 the loop wires being thereby cut off. When the post m is turned toward the left, as indicated by. the arrow, Fig. 1, the pens 0 leave the plates '11. n and the pens t t engage said plates n n, I and the current will then pass over line-wire 11?, plate n, pen 6', pen m plate m, loop-wires m m plate m, pen m pen 25, plate 'n', linewire 91), thereby including the loop. The

switch or cut-out is hence in shunt to the lamp or lamps in the loop on m WVhen the switch is placed in shunt to alamp, the resistance of 2 is so great as compared with the carbon filament that but a small proportion passes through it; but if the carbon should break, the entire current passes through the said resistant, locally heating it, thereby decomposing, reducing, or otherwise changing its nature, form, and consistency, so that the spring is allowed to press the pluge against the piece 1', and thereby form a direct contact and affording a path of low resistance for the current. If by such local heating the resistant is not entirely removed, the remaining particles are good conductors, and hence offer no resistance, as when the entire current passes through it the oxide of mercury is changed to metallic mercury and the carbon separates or burns.

In practice ithas been found that butlittle, if any, residue remains after the entire current passes through, such residue being simply dust.

I do not herein claim a switch or cut-out consisting of two conducting-pieces one of which is movable and a fusible insulator interposed between the said pieces, as the same is not of my invention. The conducting material employed by me in the switch, while being relatively a much higher resistant than the filament of the lamp, is not so high as to prevent difiusion of the current'freely through it and to thereby cause the production of a spark when the filament breaks, which spark and the results attending it are very obj ectionable.

I claim- 1. In an electric switch or cut-out, two conducting pieces or parts one of which is movable with relation to the other, combined with conducting material which ofiers considerable resistance to the current which always diffuses freely through it, said conducting material being interposed between the said conducting pieces or parts and by local heating releasing the movable conducting piece or part, as and for the purposes set forth.

2. In an electric switch or cut-out, the frame comprising the pieces, as b c, joined by insulating-strips, the spring-controlled piece 6, and the screw i, combined with conducting material which oifers considerable resistance to the current which always freely difiuses through it, said conducting material being interposed between the piece 6 and screw i, and by local heating releasing the said piece 6, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

ALEXANDER BERNSTEIN.

lVitnesses: I

CHAS. H. BURKE, EWING BUCK. 

